This application claims the priority benefit of Taiwan application serial no. 89105912, filed Mar. 30, 2000.
1. Field of the Invention
The invention relates in general to a packaging method of electro-luminescence (EL) device. More particularly, this invention relates to a packaging method of organic electro-luminescence (OEL) devices.
2. Description of the Related Art
The research of electro-luminescence starts in 1960. Organic compounds have been used as the luminescence layer in an organic electro-luminescence device. Typically, the luminescence layer is sandwiched by an top metal electrode and a bottom transparent anode. According to the types of organic electro-luminescence materials, devices such as organic light-emitting diodes (OLED) and polymer light-emitting diodes (PLED) have been developed. In early eighties, the Kodak company in the United States used tri-(8-hydroxyquinoline)aluminum (Alq3) as the luminescence layer with the insertion of a hole injection layer between the luminescence layer and the anode to enhance the recombination efficiency. The applicability of the organic electro-luminescence devices is thus confirmed. In 1990, the University of Cambridge fabricated organic light-emitting diodes using conjugated polymer such as poly(p-phenylene vinylene) (PPV). Since the material of poly(p-phenylene vinylene) has the characteristics similar to a semiconductor, and a polymer light-emitting diode can be formed with a simple fabrication process, a second trend of research was evoked. Characteristics of the organic electro-luminescence such as self-luminescence, wide vision angle (up to 160xc2x0), high response speed, low driving voltage, full color have been put in practical use such as small display panels, outdoor display panels, computer and TV screens.
As mentioned above, two types of devices, organic light-emitting diodes and polymer light-emitting diodes have been developed. The efficiency and working lifetime depend on the organic material properties, fabrication process parameters and the environment parameters of fabrication process. Furthermore, a good package is a crucial factor to maintain the device performance. In the technique point of view, currently, the material synthesis and the development of fabrication process have been commercialized. However, a quick and effective packaging method is still under development to hold the organic electro-luminescence devices in the stages of experiment or prototype without stepping into a mass production stage.
FIG. 1A and FIG. 1B shows a conventional packaging method for an organic electro-luminescence light-emitting diode. In FIG. 1A, a glue bumping machine is used to coat an ultra-violet glue (UV glue) 104 at a peripheral of an organic light emitting diode 102 on a glass substrate 100. In FIG. 1B, a glass plate 106 is laminated with the glass substrate 100 via the UV glue 104 to cover the organic light-emitting diode 102. An ultra-violet light is used to shine on and cure the UV glue 104, the package of the organic light-emitting diode 102 is thus completed.
FIG. 2A to FIG. 2B shows another conventional packaging method of organic light-emitting diodes. In FIG. 2A, a drawing metal lid 206 is disposed on a gauge (not shown). Using a glue bumping machine to coat an UV glue 204 on an edge of the metal lid. A moisture absorption sheet 208 is formed on an inner surface of the metal lid 206. The metal lid 206 in the gauge is positioned at which a light-emitting device on a glass substrate is to be packaged. In FIG. 2B, a glass substrate 200 with an organic light-emitting diode 202 is laminated with the metal lid 206 via the UV glue 204. Using an UV light to shine on the UV glue 204, the organic light-emitting diode 202 is thus packaged in the glass substrate 200 and the metal lid 206.
Both of the above packaging methods can be applied in manufactures for mass production. However, by simply using the UV glue cannot block the external moisture and oxygen. Without effectively blocking the external moisture and oxygen, the device quality and performance are thus seriously affected. Moreover, to use the UV glue at a peripheral of the light-emitting device on the glass substrate, a positive pressure, that is, a pressure larger than the atmosphere, is required within the package, for example, highly pure nitrogen can be filled. Nevertheless, this is not easy to achieve with additional fabrication cost. In addition, the production efficiency is also affected to reduce the yield of products.
FIGS. 3A to 3B further show another conventional packaging method for an organic light-emitting diode. In FIG. 3A, a glass substrate 300 comprising an organic light-emitting diode 302 is provided. A glue bumping machine is used to coat an epoxy resin (so-called AB glue) 304 on a surface of the organic light-emitting diode 302. In FIG. 3B, a glass plate 306 is used to cover the organic light emitting diode 302 and laminated with the glass substrate 300 via the epoxy resin 304. The epoxy resin 304 is then naturally cured to complete the package of the organic light-emitting diode 302.
The packaging method applies the epoxy resin 304 all over the organic light-emitting diode 302. A better packaging effect is achieved. One drawback of this kind of packaging method is that the uniformity of the epoxy resin is difficult to control for mass production. In addition, while laminating the glass substrate and the glass plate or a metal lid, an overfill of the epoxy resin occurs to cover the wiring connection between the organic light-emitting device and external devices. Thus, the organic light-emitting diode cannot be functioned properly. In addition, bubbles are easily formed between the epoxy resin and the glass plate during lamination to give rise of other side effects.
The invention provides a packaging method for an electro-luminescence device to effectively block external moisture and oxygen, so as to prevent quality deterioration and performance degradation of the electro-luminescence devices. In addition, the packaging method provided by the invention provides a high production efficiency and a product yield with reduced fabrication cost, so that the mass production can be achieved. More specifically, the problem of glue overfilling between the covering plate and the substrate is resolved. This method is particularly applicable of the packages for mass production of organic light-emitting diodes.
In the packaging method provided in the invention, a glass substrate with organic electro-luminescence diodes and a glass plate is provided. The moisture and oxygen for fabrication environment is controlled. At a peripheral of the glass plate, a frame or peripheral glue is coated to enclose the organic electro-luminescence diode after the glass plate is laminated with the glass substrate. The peripheral glue is opened with an opening. The opening is to be positioned on the glass substrate at which there is no circuit. The glass plate and the glass substrate are then laminated via the frame glue, and the frame glue is then cured. The substrate is then cut to separate individual electro-luminescence device packaged by the glass plate and the frame glue. The package of the electro-luminescence device is then disposed into a vacuum cavity. When the pressure of the vacuum cavity reaches a certain value, the glass substrate is immersed into a glue tub in the vacuum cavity. The opening is thus in contact with a packaging material. The pressure is raised to cause a pressure difference between the vacuum cavity and the cavity enclosed by the peripheral glue between the glass substrate and the glass plate. Therefore, the space is filled with the packaging material. The organic electro-luminescence device is thus encapsulated with the packaging material. The packaging material is then cured in the next step.
Both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the invention, as claimed.